How can mango dew spots be prevented and controlled effectively?

SummaryTree care: Improve the tree's immunity and disease resistance by supplementing organic matter and chemical fertilizers. Regularly spray protective fungicides and organic chelated calcium fertilizer: prevent pathogen infection, strengthen fruit flesh cells, promote the fruit's wax coating, thereby achieving the effect of preventing dew spots. Use regulators reasonably: Excessive regulators will harm the fruit, especially in the middle and late stages, so use should be reduced as much as possible. Combine internal and external measures: Supplement sufficient calcium and boron elements, strengthen the mango tree to promote wax coating.

Mango dew spot is a major disease in off-season mango production in Hainan, mainly caused by Cladosporium cladosporioides. Some studies also suggest that mango dew spot is related to pesticide and fertilizer management during the fruiting period or to calcium nutrient deficiency during the fruiting period, and there is also evidence that it is related to the fruit's wax coating, which is related to calcium nutrient supplementation in mango fruit.

In fact, before 2000, there was no such thing as mango dew spot. It was not until around 2010 that dew spot broke out on a large scale, and this period happened to be the time when excessive regulators were being used across the board. Many fruit growers blindly pursued mango size, increased the amount of regulators used, and did not pay attention to management and cultivation environment, which led to the emergence of this phenomenon.

I. Causes of mango dew spot formation

1. Caused by improper orchard site selection. When the planting area has heavy dew, is humid, and often has cloudy and rainy weather, dew spots are prone to occur. Choosing a sunny site can reduce the probability of occurrence.

2. Due to improper management, branches become too dense and lack ventilation, resulting in weak tree vigor and greatly reduced disease resistance. At this time, dew spots are prone to form.

3. Excessive use of hormones can cause the fruit skin to become thinner and can also harm the tree body, reducing its immunity and leading to the formation of dew spots.

II. Prevention methods for mango dew spot

1. Tree care

(1) By supplementing organic matter, chemical fertilizers, and caring for roots, a good tree body can be formed, improving tree immunity and disease resistance.

(2) According to soil structure and operational convenience, supplement organic fertilizer or organic water-soluble fertilizer.

(3) Use compound fertilizer reasonably, care for roots and trees, and improve the overall immunity and disease resistance of the tree.

(4) Although this will lead to higher input costs (or because the trees are contracted, one may be unwilling to invest these costs), it can be achieved through the joint efforts of all parts of the industry. For example, some relatively cost-saving methods can of course be found. Some trees are relatively cheap, about 3 yuan per tree per year, which most people can generally afford, and the value generated for society will exceed the investment.

(5) If the goal is truly to reduce the occurrence of diseases, basic work must be done well, such as tree care. Only then will there be a healthier tree body, various diseases will be reduced, and costs will be lower, making management easier.

2. Regularly spray protective fungicides and organic chelated calcium fertilizer

(1) The purpose is to prevent pathogen infection, directly supplement calcium nutrition to the fruit, strengthen fruit flesh cells, promote the fruit's wax coating, and prevent dew spots.

(2) The method of using organic chelated calcium fertilizer is to regularly spray organic chelated calcium fertilizer on the leaves after fruit setting.

(3) It can also promote the fruit's wax coating and prevent dew spots. It strengthens the fruit cell wall, prevents fruit cracking, hollow fruit, watery rot, and improves fruit disease resistance.

3. Use regulators reasonably

(1) Appropriately reduce the continuous use of agents with strong systemic activity. It is recommended to reduce the use of regulators in the middle and late stages, especially after stopping elongation agents.

(2) The use of regulators is very important, but the dosage must be noted and must not be excessive.

(3) Because although it will not produce visible disasters, each excessive use of regulators is a kind of harm to mango. Blindly pursuing mango size is by no means a healthy management method.

(4) In addition, agents with strong systemic activity easily harm the fruit skin and destroy the fruit wax. Especially in the middle and late stages, reduce or use such agents at intervals as much as possible to avoid causing excessive pressure and harm to the fruit skin.

4. Combine internal and external measures

(1) Promote wax coating, improve mango disease resistance, and reduce dew spots.

(2) A healthy mango tree body and sufficient calcium and boron supplementation help mango wax coating.

(3) Uniform wax coating is very important for mango, because at this time mango is difficult to soak in dew or humid weather.

(4) If soaked, it only stays on the fruit wax and does not come into contact with the fruit skin, which can protect the fruit skin.